Reciprocating sanding machine



2 Sheets-Sheet 1 E. HARTMANN April 15, 195s RECIPROCATING SANDING MACHINE Filed Feb. 20, 1956 51E-LEZ.

April 15, 195 E. HARTMANN RECIPROCATING SANDING MACHINE Filed Feb. 2o. 195e 2 Sheets-Sheet 2 1N ENTolL Maf/arlY msm By Clam Hartz/w1 m me ff rm/Vey RECIPROCATING SANDING MACHINE Eric Hartmann, deceased, late of Syracuse, N. Y., hy Clara Hartmann, executrix, Syracuse, N. Y., assignatto Porter-Cable Machine Company, Syracuse, N. Y., u corporation of New York Appiicstion'rebmm-y zo, 195s, set-iai No. 566,506

sv claims. (ci. s1--1-m) This invention relates to portable power-operated sanding machines of the reciprocating type.

The invention has as an object a bodily manipulable power-operated sanding machine of the reciprocating type embodying a light weight compact structural arrangement which is particularly economical to manufacture and which will operate over long periods of time without repairs or maintenance.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

vIn describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

ln the drawings- Figure 1 is a side elevational view of a sanding machine embodying my invention, the lower portion of the machine being shown in vertical section on a line corresponding to line 1 1, Figure 2;

Figure 2 is a view taken on line 2 2, Figure l;

Figure 3 is a view taken on line 3 3, Figure l;

Figure 4 is a view taken on line 4 4, Figure l; and

Figure 5 is a view, similar to Figure 4, illustrating a modified form of bearing cup.

The machine consists of a base member having a top wall with -a ange 11 depending from the periphery thereof. The top wall is formed with a gear cornpartment 12, the lower end of which is provided with a closure cap 13 detachably secured to the base as by screws, one of which is shown at 14 in Figure 1. Aligned bearing bushings 15 are mounted in the top wall and cap 13 respectively, anda j-acl: shaft 16 is journalled in these bearings and provided with a gear 18 arranged in the gear compartment 12 in mesh with a driving pinion 19 formed on the lower end of a power shaft 20.

A motor housing 22 formed with a handle portion 23 is mounted upon the top wall 10 of the base. A driving motor is mounted in the housing 22 with its power shaft disposed vertically and extending into the gear compartment 12.

A pair of supports 24 depend from the top wall 10 in spaced apart relation'. In the disclosure, the support members are in the nature of angle brackets formed from sheet material. The top wall 10 of the base being formed on its under side with pads 26 on which the supports are mounted and to which they are secured, as by screws 27. The supports 24 are formed at their lower ends with aligned apertures in which bushings 30 of wear resisting material, such as nylon, are mounted. The function of the supports 24 is to support an abrasive pad for reciprocation. The pad 32 is secured to a plate 35 which, in the illustrated form, is secured to an upper plate 36, as by screws 37 threading into apertures 38.

arent O 37 of strain.

means for interlocking the plates and relieving the screws A sheet of abrasive material 44 is positioned on the under side of the pad 32, the ends of the sheet being txedly secured by suitable spring clamps 45.

The lower portion of the jack shaft 16, projecting downwardly from the gear compartment 12, carries an eccentric member 46. The lower end of the shaft 16 is formed with a flattened surface 48 and the bore of the eccentric 46 is of complemental shapeV whereby the eccentric is secured to the shaft against rotation relative thereto. The eccentric is encircled by an anti-friction bearing 49, the bearing being 4retained in position, and the eccentric retained on the shaft 16, by a washer 50 having its marginal portion overlapping the inner race of the bearing and being apertured to receive a screw S1 threading into the shaft 16, see Figure 1. The bearing 49 is enclosed in a cup-shaped member 54 and this member is positioned between a pair of lugs 55 extending upwardly from the plate 36, these lugs being economically provided in the form of portions or tabs bent upwardly from the plate 36. Thecup member 54 is formed of anti-friction material, such as nylon, and the periphery of the side wall of the member may be of circular form, as shown in Figure 4. With this arrangement, the cup member 54 is free to rotate with the outer race of the hearing to effect uniform wear on the periphery of the cup member.

The peripheral surface of the cup member may be provided with a series of at surfaces, as illust-rated in the hexagonal form shown in Figure 5. This arrangement provides a greater wear area engaging the projections 55 and, should a pair of these'fiat surfaces develop excessive wear, the cup member can be rotated to position another pair of the flatsurfaces for engagement with the projections 55. v

The eccentric' member 46- is formed with integral counterbalancing sections 60, 61. These sections larev of semi-circular form and serve to counterbalance the reciprocation of the pad structure.

What is claimed is:

l. A portable power-operated sanding 4machine of the reciprocating type comprising a base member having a top wall formed with a gear compartment, a-motor mounted on'said top wall and having a vertically dis- The plate 36 is bent upwardly, as at 4t), and laterally to l posed power shaft extending into said gear compartment, a jack shaft journalled in said gear compartment and having an end portion depending therefrom, a pair of spaced apart rigid bearing supports depending from said top wall and being lixedly secured thereto, said supports being formed with aligned apertures, an abrasive pad supporting plate having spaced apart portions offset upwardly from the plate and being slidably positioned in f' said apertures, means operatively connecting the lower end of said jack shaft to said plate and being operable to effect reciprocation of said plate upon rotation of said jack shaft, and an abrasive pad carried by said plate.

' 2. A.' portable power-operated sanding machine of the.

reciprocating type comprising a base member having a top wall portion formed with a gear compartment, a

motor housing mounted on said top wall, a motor mounted in said housing and having its power shaft disposed vertically and extending into the gear compartment, a jack shaft journalled vertically in the gear compartment, |and gearing arranged in said compartment and operatively connecting the power shaft of said motor to said jack shaft, said top wall having a pair of depending spaced apart rigid bearing supports tixedly secured thereto, said supports being formed with aligned apertures, an abrasive pad supporting plate having spaced apart portions, offset vertically from said plate, slidably mounted in said apertures, said plate being formed intermediate said o'tset Aportions with spaced apart upwardly extending lugs, an

3` eccentric member fixcdly mounted on the lower end of said jack shaft and beingtcooperable with said upwardly extending lugs to effect reciprocation of said plate upon rotation of said jack shaft, and an abrasive pad carried by said plate.

3. A sanding machine 'as dencd in claim 2 wherein said lugs consist ofintegral portions bent lupwardly from said pad supporting plate.

4. A portable power-operated sanding machine of the reciprocating type comprising a base member having a top wall portion formedwith a gear compartment, a motor housing mounted on said top wall, amotor mounted in said housing and having its shaft disposed vertically and extendinginto the gear compartment, a jack shaft journalled vertically in the gear compartment and gearing arranged in said compartment and operatively connecting the power shaft of said motor to said jacl; shaft, said top wall having a pair of depending spaced yapart rigid bearing supports xedly secured thereto, said supports being formed with aligned apertures, ani-abrasive pad vdiametrically of said cup-shaped member and siidably 'engaging opposite sides thereof, and an abrasive pad carried by said plate.

5. A' portable power-operated sanding machine of the reciprocating type,comprising a base member having a top wall portion formed with an enclosed gear compartment, a motor housing mounted on said top wall, a motor mounted in said housing and having its shaft disposed vertically and extending into said gear compartment, a jack shaft journalled vertically in the gear compartment, and gearing arranged in said compartment and operatively connecting the power shaft of said motor to said jack shaft, a pair of rigid bearing supports detachably secured to the top wall of said base member and depending therefrom in spaced apart relation, a bearing carried by cach of said bearing supports, an abrasive pad supporting plate having integral vertically offset portions slidably mounted in said bearings, an eccentric secured to the lower end of said jack shaft, said pad supporting plate being formed with a pair of integral upwardly extending projections disposed in spaced apart relation,

`a bearing positionedwon said eccentric, a cup-shaped member positioned on said bearing intermediate` said upwardly extending projections .and slidabiy engaging the same whereby to impart reciprocation of said pad lsupporting plate upon rotation vof said jack shaft, and 4 an abrasive pad carried by saidplate.

References Cited'in the file of patent UNITED STATES PATENTS Champayne June 26, 

